David B. Larson MD, Presenter: Nothing to Disclose

Lara W Johnson MD, Abstract Co-Author: Nothing to Disclose

Beverly M Schnell PhD, Abstract Co-Author: Nothing to Disclose

Shelia Salisbury PhD, Abstract Co-Author: Nothing to Disclose

Howard Paul Forman MD, Abstract Co-Author: Nothing to Disclose

To describe nationwide trends and factors associated with utilization of Computed Tomography (CT) in the emergency department (ED).

This study was exempt from Institutional Review Board oversight. Nationally-representative data from the 1995-2007 National Hospital Ambulatory Medical Care Surveys were used to evaluate the number and percent of ED visits associated with CT. A mean of 30,044 visits were sampled each year. Data were subcategorized according to multiple patient characteristics, including age, gender, race, admission/transfer status, and source of payment, as well as hospital characteristics including geographical region, population density, hospital ownership, and ED teaching status. Rao-Scott chi-square was performed to test whether CT utilization was similar across subpopulations. Data were evaluated according to exponential and logistic growth models. Utilization was also evaluated according to chief complaint.

From 1995-2007, the number of visits with CT increased from 2.7 million to 16.2 million, a 5.9-fold increase, averaging 16% per year. Only 3.3% of the 16% average annual growth was explained by increasing patient volume; the remaining 12.7% increase was explained by increasing frequency of CT scanning. The percent of visits associated with CT increased from 2.8% to 13.9%, a 4.9-fold increase, averaging 14.2% per year. An exponential growth model provided the best fit for the trend in CT utilization. Utilization was greater in older patients, white patients, patients admitted to the hospital, and at facilities in metropolitan regions. By the end of the study period, the top chief complaints among those receiving CT were abdominal pain, headache, and chest pain. Percent of patients undergoing CT increased for all evaluated chief complaints, most substantially for flank pain, abdominal pain, and chest pain.

Utilization of CT in the ED has increased at a higher rate than that reported in other settings. We find no evidence that overall CT utilization had begun to taper by 2007.

By 2007, CT use in the ED had not begun to taper, indicating that factors promoting its use continued to predominate over factors that limit its use.

Larson, D, Johnson, L, Schnell, B, Salisbury, S, Forman, H, National Trends in CT Utilization in the Emergency Department,1995-2007.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9001484.html